Abstract
Ewing Sarcoma (EwS) is a rare pediatric malignancy characterized by a unique t(11:22) (q24;q12) translocation resulting in the pathognomonic EWSR1::FLI1 fusion. Recent reports indicate that the EWSR1::FLI1 oncofusion drives aberrant expression of numerous transcripts, including Lipoxygenase Homology Domains 1 (LOXHD1). Given its highly restricted protein expression pattern and role in EwS tumorigenesis and metastasis, LOXHD1 may serve as a novel immunotherapeutic target in this malignancy. LOXHD1 immunogenic epitopes restricted to HLA-A*02:01 allowed for the isolation of a high avidity αβTCR. LOXHD1-specific TCR engineered CD8+ T cells conferred cytotoxic activity against a panel of HLA-A*02:01+ EwS tumor cell lines and adoptive transfer led to tumor eradication in a mouse xenograft model of EwS. This study nominates LOXHD1 as an oncofusion regulated, non-mutated tumor associated antigen (TAA) with expression limited to inner hair cells of the cochlea, adult testis, and EwS.